Visual indicator for an aerosol medication delivery apparatus and system

ABSTRACT

A flow indicating system that includes a conduit that contains a substance, wherein the conduit defines a path along which the substance primarily flows and a viewing port attached to the conduit and the viewing port prevents substantially non-ambient atmosphere gases and substances from escaping therefrom and allows visualization of an internal space defined by the viewing port. A flow indicator that is positioned within the conduit so as to be viewed via the viewing port and is positioned so as to not to substantially interfere with a flow of the substance along the path.

This application is a continuation of U.S. patent application Ser. No.11/130,808, filed May 17, 2005, which claims the benefit of U.S. patentapplication Ser. no. 10/431,325, filed May 7, 2003, now U.S. Pat. No.6,904,908, which claims the benefit of U.S. Provisional PatentApplication 60/382,227, filed May 21, 2002, the entire disclosures ofwhich are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a visual indicator for an aerosolmedication delivery apparatus and system used for administering a dosageof a substance in aerosol form to a patient.

2. Discussion of Related Art

The use of an aerosol medication delivery apparatus and system toadminister medication in aerosol form to a patient's lungs by inhalation(hereinafter “aerosol delivery system(s)”) is well known in the art. Asused herein: the term “substance” includes, but is not limited to, anysubstance that has a therapeutic benefit, including, without limitation,any medication; the term “patient” includes humans and animals; and theterm “aerosol delivery system(s)” includes pressurized metered-doseinhalers (pMDIs), pMDI add-on devices, such as holding chambers, devicesincluding a chamber housing and integrated actuator suited for a pMDIcanister, nebulizers and dry powder inhalers. Examples of such aerosoldelivery systems are disclosed in U.S. Pat. Nos. 4,627,432, 5,582,162,5,740,793, 5,816,240, 6,026,807, 6,039,042, 6,116,239, 6,293,279,6,345,617, and 6,435,177, the entire contents of each of which areincorporated herein by reference. Conventional pMDIs typically have twocomponents: 1) a canister component in which the medication particlesand a propellant are stored under pressure in a suspension or solutionform and 2) a receptacle component used to hold and actuate the canisterand having a mouthpiece portion. The canister component typicallyincludes a valved outlet from which the contents of the canister can bedischarged. A substance is dispensed from the pMDI by applying a forceon the canister component to push it into the receptacle componentthereby opening the valved outlet and causing the medication particlesto be conveyed from the valved outlet through the receptacle componentand discharged from an outlet of the receptacle component. Upondischarge from the canister, the substance particles are “atomized” toform an aerosol.

In the case of pMDI holding chambers, the holding chambers typicallyinclude a chamber housing with a front end and a rear end. Themouthpiece portion of the pMDI receptacle is received in an elastomericbackpiece located at the rear end of the chamber housing. An example ofsuch a backpiece is disclosed in U.S. Pat. No. 5,848,588, the entirecontents of which are incorporated herein by reference. The front end ofthe chamber housing includes an inhalation valve or a containment baffleor both and an interface, such as an adapter, a mouthpiece and/or amask. The interface can be coupled to the front end of the chamberhousing or integrally molded to the front end of the chamber housing.Some holding chambers include an integrated receptacle for a pMDIcanister thereby eliminating the need for a backpiece or otherequivalent structure used to receive and hold the mouthpiece portion ofa pMDI.

One problem that currently exists with many aerosol delivery systems isthat there is a lack of a visual indication to alert a caregiver when apatient is inhaling. In the case of a pMDI used in conjunction with aholding chamber, for example, it is important for a caregiver to know ifthe patient is inhaling at a rate sufficient to open the inhalationvalve to allow the aerosolized medication to exit the holding chamber.It is also important to know when the patient is inhaling in order tocoordinate the actuation of the pMDI with inhalation.

The present invention proposes to overcome the above-described problem,and other problems as described further below, by using a visualindicator in an aerosol delivery system. Such a visual indicator isparticularly helpful with patients who do not have established breathingpatterns. These patients, such as infants and small children, generallyhave very low tidal volumes.

Some known holding chambers on the market maintain that it is possibleto determine breathing patterns by looking through the chamber for themovement of the inhalation valve. This is difficult to do in the case oflow tidal volumes when the valve will only move a minor amount. If thechamber has an accumulation of drug deposited on the walls then thisfurther impedes the viewing. Several examples of such devices arediscussed below. First, U.S. Pat. No. 5,385,140 discloses a holdingchamber that has a crosscut valve with four petals that lift duringinhalation. At lower tidal volumes the petals will lift a small amount,but this can be difficult to see since there are numerous supportingribs directly in the line of sight. A second device is disclosed in U.S.Pat. No. 6,039,042 where a clear adapter is used to view breathingpatterns by way of the valve. However, the inhalation portion of thevalve that moves is directly in the drug pathway and has only slightmovement at lower flow rates (approximately 20°). Note that the entirecontents of U.S. Pat. Nos. 5,385,140 and 6,039,042 are incorporatedherein by reference.

With some of the other devices on the market it is possible to view theexhalation portion of the breath, but this is not considered to be asimportant as seeing the inhalation portion. One such device is disclosedin U.S. Pat. No. 6,293,279, the entire contents of which areincorporated herein by reference. The device has a mask with anexhalation valve that moves during exhalation, but at the lower tidalvolumes this movement is not obvious.

Another problem that occasionally occurs, when the interface includes amask, is a poor seal between the patient's face and the mask. Such apoor seal may adversely affect the delivery of aerosolized medication tothe patient. The use of the above-mentioned visual indicator would behelpful in alerting the caregiver to verify whether there is a poor sealbetween the patient's face and the mask and, if so, to readjust the maskon the patient's face to improve the seal.

SUMMARY OF THE INVENTION

One aspect of the present invention regards a delivery system thatincludes a chamber that contains a substance in an interior volume ofspace formed within said chamber and an opening that receives thesubstance located in said volume of space and introduces the substanceto a downstream path upon which the substance primarily flows along. Aninterface that receives the substance from the opening, the interfacehas a viewing port that prevents substantially non-ambient atmospheregases and substances from escaping therefrom and that allowsvisualization of an internal portion of the interface. A flow indicatoris positioned within the interface so as to be viewed via the viewingport and is positioned so as to not substantially interfere with a flowof the substance along the path.

A second aspect of the present invention regards a method of determiningwhether a patient is inhaling or exhaling when using a delivery system,the method including dispensing a substance located within an interiorvolume of a delivery system so that the substance will primarily flowalong a path within the delivery system after being dispensed. Observinga position of a flow indicator located within the delivery system andlocated so as not to substantially interfere with the substance flowingalong the path. Determining whether a user of the delivery system isinhaling from the delivery system based on the observed position of theflow indicator.

A third aspect of the present invention regards a flow indicating systemthat includes a conduit that contains a substance, wherein the conduitdefines a path along which the substance primarily flows and a viewingport attached to the conduit and the viewing port that preventssubstantially non-ambient atmosphere gases and substances from escapingtherefrom and allows visualization of an internal space defined by theviewing port. A flow indicator that is positioned within the conduit soas to be viewed via the viewing port and is positioned so as to not tosubstantially interfere with a flow of the substance along the path.

Each aspect of the present invention provides the advantage of assistingeither the patient or a third party caregiver to determine when thepatient is inhaling when using an aerosol delivery system so that thepatient or third party caregiver can be alerted to possible causesaffecting inhalation, such as an improper seal between the patient'sface and the aerosol delivery system's interface, such as a mask.

Each aspect of the present invention provides the advantage of allowinga user or caregiver to observe when inhalation has begun so that thedrug can be properly administered.

The foregoing and other features and advantages of the invention willbecome further apparent from the following detailed description of thepresently preferred embodiments, read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of an aerosol deliverysystem in accordance with the present invention;

FIG. 2 is a perspective and partially transparent view of the aerosoldelivery system of FIG. 1;

FIG. 3 is a side cross-sectional view of the aerosol delivery system ofFIG. 1;

FIG. 4 is a perspective exploded view of the aerosol delivery system ofFIG. 1;

FIG. 5 is a front perspective view of an embodiment of an adapteraccording to the present invention to be used with the aerosol deliverysystem of FIG. 1;

FIG. 6 is a rear perspective view of the adapter of FIG. 5;

FIG. 7 is a front view of the adapter of FIG. 5;

FIG. 8 is a rear view of the adapter of FIG. 5;

FIG. 9 is a cross-sectional view of the adapter of FIG. 5 taken alongline 9-9 of FIG. 7;

FIG. 10 is a cross-sectional view of the adapter of FIG. 5 taken alongline 10-10 of FIG. 7;

FIG. 11 is a cross-sectional view of the adapter of FIG. 5 taken alongline 11-11 of FIG. 8;

FIG. 12 is a front perspective view of a second embodiment of an adapteraccording to the present invention to be used with the aerosol deliverysystem of FIG. 1;

FIG. 13 is a rear perspective view of the adapter of FIG. 12;

FIG. 14 is a front view of the adapter of FIG. 12;

FIG. 15 is a side view of the adapter of FIG. 12;

FIG. 16 is a front perspective view of an embodiment of a valveaccording to the present invention to be used with the aerosol deliveryapparatus of FIG. 1;

FIG. 17 is a rear perspective view of the valve of FIG. 16;

FIG. 18 is a front view of the valve of FIG. 16;

FIG. 19 is a rear view of the valve of FIG. 16;

FIG. 20 is a cross-sectional view of the valve of FIG. 16 taken alongline 20-20 of FIG. 18;

FIG. 21 is a cross-sectional view of the valve of FIG. 16 taken alongline 21-21 of FIG. 20;

FIG. 22 is a front perspective view of a second embodiment of a valveaccording to the present invention to be used with the aerosol deliveryapparatus of FIG. 1;

FIG. 23 is a rear perspective view of the valve of FIG. 22;

FIG. 24 is a front view of the valve of FIG. 22;

FIG. 25 is a perspective view of an embodiment of a retaining discaccording to the present invention to be used with the aerosol deliverysystem of FIG. 1;

FIG. 26 is a side-view of the retaining disc of FIG. 25;

FIG. 27 is a side cross-sectional view of an embodiment of an aerosoldelivery system according to the present invention taken along line27-27 of FIG. 28 that can be used with the aerosol delivery system ofFIG. 1;

FIG. 28 is a front view of the aerosol delivery system of FIG. 27;

FIG. 29 is an enlarged portion of the circled area of the aerosoldelivery system of FIG. 27;

FIG. 30 is a side and partially transparent view of the aerosol deliverysystem of FIG. 1 showing exhalation and inhalation paths;

FIG. 31 is a side and partially transparent view of a portion of theaerosol delivery system of FIG. 1 showing a flow indicator at a restposition;

FIG. 32 is a side-cross sectional view of the aerosol medicationdelivery system of FIG. 1 showing a flow indicator at a rest position;

FIG. 33 is a side and partially transparent view of a portion of theaerosol medication delivery system of FIG. 1 showing a flow indicator atan inhalation position;

FIG. 34 is a side-cross sectional view of the aerosol delivery system ofFIG. 1 showing a flow indicator at an inhalation position;

FIG. 35 shows a perspective and exploded view of a second embodiment ofan aerosol delivery system according to the present invention;

FIG. 36 shows a perspective and exploded view of a third embodiment ofan aerosol delivery system according to the present invention;

FIG. 37 shows a perspective view of a fourth embodiment of an aerosoldelivery system according to the present invention;

FIG. 38 shows a perspective, exploded view of an embodiment of a drypowder inhaler delivery system according to the present invention;

FIG. 39 shows a perspective view of the dry powder inhaler deliverysystem of FIG. 38;

FIG. 40 shows a perspective view of an embodiment of a nebulizerdelivery system according to the present invention;

FIG. 41 shows a perspective, exploded view of an embodiment of a holdingchamber and adapter according to the present invention to be used withthe nebulizer delivery system of FIG. 40; and

FIG. 42 shows a perspective view of the holding chamber and adapter ofFIG. 41;

FIG. 43 shows a rear view of an alternative embodiment of an adapter;and

FIG. 44 shows a retainer releasably connected to the adapter shown inFIG. 43.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1-11, 16-21 and 25-29 show an embodiment of an aerosol deliverysystem 100. The system 100 includes a holding chamber or conduit 102, aninterface 104, a retaining disc 116, an inhalation valve 132 and asource of a substance, such as a pMDI canister 106, attached to the rearend of the holding chamber 102.

As shown in FIGS. 1-4 and 27-34, the holding chamber 102 includes achamber housing 108 that has a generally cylindrical cross-sectionalshape that defines an interior volume of space for receipt therein ofaerosolized medication from the pMDI 106. A front end of the chamberhousing 108 includes a dome-shaped head piece 110 that includes acentral circular opening 112 that is in fluid communication with theinterior volume of space of the chamber housing 108. The opening 112defines the periphery of a flow path as it exits the opening. The headpiece 110 further includes a plurality of engagement tabs 113, whosefunction will be described below. A rear end of the chamber housing 108is attached to a detachable and flexible backpiece 114 that includes anopening (not shown) suited to receive the mouthpiece portion of the pMDIreceptacle that houses the pMDI canister. The backpiece 114 preferablyis substantially the same as the backpiece disclosed in U.S. Pat. No.5,848,588. Examples of possible pMDI adapters and canisters to be usedin conjunction with the holding chamber 102 are also described in U.S.Pat. Nos. 5,012,803, 5,012,804, 5,848,588 and 6,293,279, the entirecontents of each of which is incorporated herein by reference.

When a force is applied to the stem of the pMDI canister a portion ofthe substance is discharged from the discharge end of the pMDIreceptacle in aerosol form into the chamber housing 108. The aerosolmedication particles within the chamber housing 108 are withdrawntherefrom by having the patient inhale through the interface 104 in themanner described below.

The pMDI canister contains a substance, preferably a medicationsuspension or solution under pressure. In the present embodiment, thesubstance dispensed is an HFA propelled medication suspension orsolution formulation. Other propellants, such as CFC may also be used.It should be pointed out that while the described embodiments regard anaerosol delivery system for the delivery of an aerosolized medicationfrom a pMDI, other aerosol delivery systems are contemplated that can beused within the spirit of the present invention. For example, it iscontemplated that a visual indicator can be incorporated with an aerosoldelivery system such as existing ventilator systems, dry powder inhalersand nebulizers, in a manner similar to that described below. Examples ofnebulizers that can be adapted to include a visual indicator aredisclosed in U.S. Pat. Nos. 5,823,179 and 6,044,841, the entire contentsof which are incorporated herein by reference.

The present invention is not limited to the treatment of human patients.For example, it is contemplated that a visual indicator can beincorporated in a mask for administering medication to animals,including for example and without limitation equines, cats, dogs, etc.An example of an equine mask is disclosed in U.S. Pat. No. 5,954,049,the entire contents of which are incorporated herein by reference. Withsuch aerosol delivery systems in mind, the variety of medications thatcan be dispensed by aerosol delivery systems that employ a visualindicator in accordance with the present invention is increased.

As shown in FIG. 4, a retaining disc 116 is positioned before theopening 112 at the front end of the chamber housing 108. The retainingdisc 116 may be integrally attached to the chamber housing 108 orreleasably attached as shown in FIG. 4. As shown in FIGS. 4 and 25-26,the retaining disc 116 includes an annular ring 118 that surrounds anopening 120. Four linear appendages 122 extend inwardly from the annularring 118 and are attached to a circular dome portion 124. The annularring 118, the appendages 122 and the dome portion 124 define aninhalation opening area 126 that includes four openings 126A-126D. Theopenings 126A-D are arcuate in shape. The openings have an inner radiusof approximately 10 mm and an outer radius of approximately 18 mm. Eachopening has an arcuate length of 4 mm. The size, shape and number ofopenings may vary depending on the medication and/or propellant used.The retaining disc 116 is preferably made of a rigid material, such as ametal or plastic, preferably propylene or polycarbonate. As shown inFIGS. 4, 25 and 26, the retaining disc 116 includes a semi-circular stop117 whose operation will be explained below. Other examples of possibleretaining discs are disclosed in U.S. Pat. No. 6,293,279, the entirecontents of which are incorporated herein by reference. The annular ring118 is attached to the front end of the chamber housing 108 so that theopenings 112 and 120 are concentric and overlap one another.

The center portion of the retaining disc 116 includes a containmentbaffle positioned so as to partially block the opening 112. Theretaining disc 116 reduces the velocity or flow rate or both of theaerosol medication particles flowing along the axis 128 of the chamberhousing 108. The circular dome portion 124 of the retaining disc 116 isaligned with the central axis 128 of the chamber housing 108 and isdirectly in line with the opening 112. Aerosol medication particles thathave a flow path away from the central axis 128 tend to have a velocitythat is lower than that of particles near to the axis 128. The domeportion 124 of the retaining disc 116 reduces the forward, on-axisvelocity and simultaneously acts as an impaction surface for on-axisprojectile aerosol medication particles and so protects the duckbillvalve 132. At the same time, the dome portion 124 allows slower movingaerosol medication particles to migrate towards the sides 130 of thechamber housing 108. The forward velocity of the aerosol medicationparticles away from the axis 128 along the chamber length is alsoreduced by the annular ring 118 of the retaining disc 116. It should beunderstood that the dome portion can alternatively be formed with a flatsurface facing the rear end, or a curved surface, for example a convexor concave surface.

As shown in FIG. 4, a duckbill valve 132 is seated on the front surfaceof the annular ring 118. The duckbill valve 132 is generally well knownin structure having a top surface 134 and a bottom surface 136. Thesurfaces 134 and 136 open and close with respect to each other in awell-known manner so as to allow or prevent gas to flow through thevalve 132. The duckbill valve 132 preferably is a 19 mm valve made of asoft plastic, such as silicone or a thermoplastic elastomer. It shouldbe understood that other valves, including for example and withoutlimitation, center post valves, slit petal valves and valves having acentral opening with a peripheral sealing edge.

On the top portion of the duckbill valve 132, a visual flow indicator138 is integrally attached to a top portion of the outer circumferenceof the duckbill valve 132. The visual flow indicator 138 is rectangularin shape, although other shapes, such as a square or an ellipse, mayalso be suitable. For example, the visual flow indicator 138′ may have arounded top edge as shown in FIGS. 22-24. The rectangular and roundedvisual flow indicators 138, 138′ each may have a length of 5 mm to 20mm, preferably a length between 7 mm and 11 mm, and most preferably alength of 8.5 mm, a width of 5 mm-20 mm, preferably 8 mm to 12 mm, andmost preferably 10 mm, and a thickness of 0.1 to 2 mm, preferably 0.15-1mm, and most preferably 0.25 mm. The length of the visual flowindicators 138, 138′ are measured from a hinge area (not shown). Withthis in mind, the sensitivity of the visual flow indicators 138, 138′ isa function of the length of the indicator, wherein as the indicatorbecomes longer it becomes more sensitive to detecting flow. Theoperation of the visual flow indicators 138, 138′ will be described inmore detail below.

The flow indicator can be integrally formed with the valve or it can bemade as a separate member. The indicator 138, 138′ is hingedly connectedto the valve with a living hinge formed at the junction thereof, or itcan be hingedly connected with a pin. The resiliency of the indictor138, 138′ biases the indicator to an at rest position. However, itshould be understood that auxiliary springs can be configured to act onthe indicator to bias it to the at rest position.

As described above, the chamber housing 108, retaining disc 116 andduckbill valve 132 define a holding chamber 102. The holding chamber 102is attached to a patient interface 104, although a patient interfaceintegrally molded with the front end of the chamber housing 108 wouldalso be suitable. In one embodiment, the patient interface 104 includesan adapter 140 and a mask 144 with exhalation valve 142. Other patientinterfaces may include for example and without limitation, variousmouthpieces, masks, endotracheal tubes, etc. As shown in FIGS. 4-11, theadapter 140 includes an annular attachment collar 146 with slots 148, atransition piece 150 and a cylindrical exit port 152. The adapter 140 isattached to the chamber 108 by snap inserting the tabs 113 of thechamber housing 108 into the slots 148 and then twisting the chamberhousing 108 or adapter 140 so that the tabs 113 are locked into placewithin the slots 148. Once the chamber housing 108 is attached to theadapter 140, the duckbill valve 132 and the flow indicator 138, 138′ arepositioned within the transition piece 150. In particular, the flowindicator 138, 138′ is positioned within a raised viewing port area 154of the transition piece 150. Since the adapter 140 with its transitionpiece 150 and raised viewing port area 154 are each made of a clearrigid plastic, such as polycarbonate or a co-polyester, the movement ofthe flow indicator 138, 138′ is visible to a user at all times. Inanother variation, the viewing port area 154 is formed in the collar 146and the indicator 138, 138′ is positioned therein.

As explained above, the retaining disc 116 is positioned at the frontend of the chamber housing, and can be integrally attached thereto orreleasably detached, for example by disposing it between the chamberhousing and the adapter 140. In one embodiment, shown in FIGS. 43 and44, the retaining disc 116 is releasably connected to the adapter 140,or other patient interface component. In one embodiment, a plurality oftabs 123 are formed on the interior of the adapter and engage the outerperipheral edge of the annular ring 118 in a snap-fit engagement. Inother embodiments, the retaining disc is integrally molded with theadapter or other patient interface component, or is secured thereto bybonding, fasteners and other similar devices. In this way, the retainingdisc 116, and the valve 132 that is seated thereon between the adapterand the retaining disc, remain coupled to the adapter 140, or othersimilar component secured to the end of the chamber housing, upon itsremoval, for example when cleaning the device. Accordingly, the risk oflosing the retaining disc 116 and/or valve 132 is reduced.

Note that an alternate embodiment of an adapter is shown in FIGS. 12-15.The adapter 140′ has similar dimensions and elements as the adapter ofFIGS. 5-11. Operation and attachment are similar as well. One differenceis the shape of the viewing port area 154′ in which the indicator 138,138′ is positioned.

An exhalation valve 142 is inserted into an exit port formed in thenasal reception area 160 of the mask 144 and attached thereto. Examplesof such a mask and exhalation valve are disclosed in U.S. Pat. Nos.5,988,160 and 5,645,049, the entire contents of each of which areincorporated herein by reference. A cylindrical input port 156 of themask 144 is placed over the exit port 152 of the adapter 140, 140′ andattached thereto by a friction fit.

With the above description of the structure of the aerosol deliverysystem 100, the operation of the system 100 can be readily understood.In particular, a patient places his or her face within the interior 158of the mask 144 so that his or her nose is positioned within the nasalreception area 160. In other embodiments, the patient or caretakerarranges the patient interface, such as a mouthpiece or endotrachealtube in appropriate registration with the user. The patient or caretakerthen presses the pMDI canister within the pMDI adapter of the pMDI 106attached to the backpiece 114 located at the rear end of the chamberhousing 108, which causes the medication to be delivered in aerosol formto the opening 112 in the manner described previously.

At or just after the time of depressing the pMDI canister, the patientinhales. During proper inhalation, the visual flow indicator 138 willpivot forward in response to the inhalation pressure by an angle θ ofbetween 25° to 45°, and preferably 45°, and seal against a surface 162on the adapter 140, 140′ as shown in FIGS. 3 and 33-34. The angle θ canbe varied to take into account the attributes of the patient, i.e.,child v. infant. Note that the visual flow indicator 138 has minimalresistance, due to its size and shape, and will respond to low tidalvolumes, which is ideal for infants (tidal volume of approximately 50cc, flow rate approximately 5 lpm) and small children (tidal volumeranging from approximately 150 to 250 cc, flow rate approximately 12lpm). The movement of the visual flow indicator 138, 138′ againstsurface 162 creates a seal that will prevent entrainment of ambient air.A caregiver who directs his or her attention to the viewing port area154, 154′ will be able to see the movement of the flow indicator 138,138′ as it forms the seal and so will become aware that inhalation isoccurring or has occurred. Also during inhalation, the duckbill valve132 will open thereby allowing the aerosolized medication to exit thechamber housing 108 and be introduced by the opening 112 to a downstreampath upon which the medication flows along so as to eventually beinhaled by the patient. As shown in FIGS. 2 and 31-34, the flowindicator 138, 138′ is positioned above the duckbill valve 132 andoutside the periphery of opening 112, and so is outside of themedication dispensing pathway, and thus does not compromise medicationdelivery. Note that the introduction of the medication to the pathwaythrough the opening 112 can be caused by either external or internalforces.

Once the patient exhales or ceases to inhale, the flow indicator 138,138′ will pivot back to its original vertical position until it engagesthe stop 117 as shown in FIGS. 31-32. The resiliency of the indicator138, 138′ pivots or biases the indicator to the at-rest position. Again,a caregiver who directs his or her attention to the viewing port area154, 154′ will be able to see the return movement of the flow indicator138, 138′ and so will become aware that exhalation has occurred. Besidesalerting the caregiver that inhalation or exhalation is occurring or hasoccurred, the movement of the flow indicator gives the caregiverconfidence that, where the patient interface includes a mask, a properseal is formed between the patient's face and the mask 144.

Note that the flow indicator 138, 138′ does provide a pathway which isin fluid contact with ambient air located within the viewing port area154, 154′ rearward of the flow indicator 138, 138′. The pathway includesa rearward opening or an opening formed in the rearward top portion ofthe viewing port area 154, 154′, such that the flow indicator 138, 138′is drawn off of the stop. However, the flow indicator 138, 138′ sealsagainst surface 162 to prevent the entrainment of ambient air asdescribed above.

The primary pathway for exhaled gases is through the exhalation valve142 located in the mask 144 as shown in FIG. 30. In particular, the stop117 and flow indicator 138, 138′ extend so as to substantially block allexhaled gases from escaping via the viewing port while allowing ambientair to flow therein. Similarly, the stop 117 and flow indicator 138,138′, which is registered against surface 162 upon inhalation,substantially blocks the dispensed substance from exiting the deliverysystem via the viewing port area. Accordingly, the stop 117 and flowindicator 138, 138′ substantially prevents non-ambient gases andsubstances from escaping from the delivery system via the viewing portarea. Note that the stop 117 may be removed so as to allow the viewingport area to act as a two-way valve that allows ambient atmosphere toenter and exhalation gases to exit therefrom.

An alternative embodiment of an aerosol delivery system is shown in FIG.35. The aerosol delivery system 200 is the same as the aerosol deliverysystem 100 of FIGS. 1-11, 16-21 and 25-29 except that the holdingchamber and the patient interface have been altered as shown in thedrawings and as described herein. Accordingly, like elements will retainlike numerals. With this in mind, the holding chamber or conduit 202 hasa backpiece 114 attached to a rear end of the chamber housing 108. Anopening of the backpiece 114 receives a discharge end of an adapter (notshown) that houses the pMDI canister. The holding chamber 202 furtherincludes a retaining disc 216 that is integrally attached to a front endof the cylindrical chamber housing 108. The retaining disc 216 includesan annular ring 218 that surrounds an opening 220. Eight linearappendages 222 extend inwardly from the annular ring 218 and meet at acenter hub 223. The annular ring 218, the appendages 222 and the centerhub 223 define an inhalation opening area 226 that includes eightopenings. The size, shape and number of the openings may vary dependingon the medication and/or propellant used.

As shown in FIG. 35, a petal valve 232 is attached to the front surfaceof the annular ring 218. In particular, pegs 233 integrally formed onthe annular ring 218 are snugly inserted into corresponding openings 235formed in the petal valve 232. The operation of the petal valve 232 iswell known in the art. The petal valve is preferably made of a materialsimilar to that of the duckbill valve 132. On the top portion of thepetal valve 232, a visual flow indicator 138, 138′ is integrallyattached to a top portion of the outer circumference of the petal valve232.

The holding chamber or conduit 202 is attached to an interface similarto the interface 104 shown in FIGS. 1-11, 16-21 and 25-29. The interfaceof the embodiment of FIG. 35 differs from the interface 104 in that ashorter adapter 240 is used, which includes a cylindrical exit port 252that can function as a mouthpiece. Alternatively, the adapter 240 can beattached to an exhalation valve and a mask (not shown) in the mannerdescribed with respect to FIGS. 1-11, 16-21 and 25-29. As shown in FIG.35, the adapter 240 includes an annular attachment collar 246 with slots248, a transition piece 250 and a cylindrical exit port 252. The adapter240 is attached to the chamber housing 108 by snap inserting tabs 212 ofthe chamber housing 108 into the slots 248 and then twisting the chamberhousing 108 or adapter 240 so that the tabs 212 are locked into placewithin the slots 248. Once the chamber housing 108 is attached to theadapter 240, the petal valve 232 and the flow indicator 138, 138′ arepositioned within the transition piece 250. In particular, the flowindicator 138, 138′ is positioned within a raised viewing port area 254of the transition piece 250. The adapter 240 with its transition piece250 and raised viewing port area 254 are each made of a clear rigidplastic, such as polycarbonate or a co-polyester. The chamber housing108 can also be made of a clear material, such as a rigid plastic. Thus,a caregiver is able to visualize the movement of the visual flowindicator 138, 138′ within the adaptor 240 and is able to detect whetherinhalation is being performed or a proper seal is present in the samemanner as with the aerosol delivery system of FIGS. 1-11, 16-21 and25-29. The adapter can also include a stop member that interfaces withthe flow indicator.

In each of the embodiments shown in FIGS. 1-35, the visual flowindicator 138, 138′ is integrally attached to its corresponding valve.It should be pointed out that such integral attachment is not necessary.For example, it is possible to take a separate piece of material in theshape and composition of indicator 138, 138′ and attach one end to aportion of the adapter so that a free end of the material lies withinthe viewing port. Attachment can be accomplished by inserting the oneend between two ridges formed in the adapter and gluing the endtherebetween.

Another example of where the visual flow indicator is not attached to avalve is shown in FIG. 36. In this embodiment, a visual flow indicator338 is attached to an aerosol delivery system 300 similar to the onedisclosed in U.S. Pat. No. 6,293,279. One difference is that the chamberhousing 308, attached to the canister holding portion 309, includes atransparent viewing port 354. In an alternative embodiment, the viewport can be formed on the downstream portion 311 of the delivery system.The visual flow indicator 338 is attached to either the chamber housing308 or the downstream portion 311 that includes the mouthpiece 313 via asnap fit. The visual flow indicator 338 preferably has a shape and astructure similar to that of the visual flow indicators 138, 138′described previously so as to have a similar range of motion. Inoperation, the chamber housing 308 acts as a conduit of the substance asit travels to the mouthpiece 313.

Other variations for the visual flow indicator are also possible. Forexample, the viewing port area can be positioned elsewhere on theadapters 140, 240, the chamber housing 308 and the downstream portion311 and the corresponding visual flow indicator is positioned so as tobe viewed from the viewing port area. In the case of the aerosoldelivery system of FIGS. 1-11, 16-21 and 25-29, the viewing port areacan be moved to the side of the adapter 140 in the manner shown in FIG.37. In such a case, the corresponding visual flow indicator 138, 138′ ismoved to a side of the duckbill valve 132 that faces the viewing portarea 154, 154′.

FIGS. 38-42 show the present invention used in aerosol delivery systemssuch as dry powder inhalers and nebulizer systems. In the case of drypowder inhalers, a dry powder inhaler 400 includes a chamber housing 402that contains a dry powder as shown in FIGS. 38 and 39. The chamberhousing 402 is similar to the chamber housing disclosed in U.S. Pat. No.4,627,432, the entire content of which is incorporated herein byreference. Other dry powder inhalers that can incorporate a flowindicator are disclosed for example and without limitation in U.S. Pat.No. 6,116,239, which is hereby incorporated herein by reference. Thechamber housing 402 includes a circular bottom opening 404 and a topopening 406 that is in fluid communication with ambient air. Aninterface which includes a conduit or mouthpiece 408, is attached to thebottom opening 404 so that the mouthpiece 408 is in fluid communicationwith the interior of the chamber housing 402. Attached to the mouthpiece408 is a transparent viewing port area 410. Within the viewing port area410, a visual flow indicator 412 is positioned. The visual flowindicator 412 has a rear, lower slot (not shown) that receives a ridge414 formed below the top opening 406. Once the ridge 414 is received inthe rear slot, the visual flow indicator 412 is permanently attached tothe ridge 414 by using an adhesive.

In operation, the patient activates the chamber housing 402 to provideaccess to the dry powder within by having the patient inhale through themouthpiece 408. Upon inhalation, the dry powder substance within thehousing 402 is introduced by the opening 404 to a downstream path alongwhich the substance travels through the interface and the mouthpiece 408to reach the patient. During inhalation the upper part of the visualflow indicator 412 will pivot downward to a horizontal position. If thepatient is not inhaling or fails to inhale above a specified rate ofinhalation, the upper part of the visual flow indicator 412 will remainin a vertical position blocking top opening 406. The range of motion ofthe visual flow indicator 412 is preferably the same as that of thevisual flow indicators 138, 138′ and 338 mentioned previously.

A visual flow indicator can also be used in nebulizer systems. Anebulizer 500 includes a chamber housing 502 that contains a liquidsubstance as shown in FIGS. 40-42. The chamber housing 502 is similar tothe chamber housing disclosed in U.S. Pat. No. 5,823,179. The chamberhousing 502 includes a rectangular-like exit port 504 that includes anopening (not shown). An interface includes an adapter 506 that isattached to the exit port 504 so as to be in fluid communication withthe interior of the chamber housing 502. The interface also includes amouthpiece 508 which is attached to the adapter 506 so that themouthpiece 508 is in fluid communication with the interior of thechamber housing 502 via adapter 506. Attached to the adapter 506 andmouthpiece 508 are transparent housings 510, 512, respectively. When themouthpiece 508 is attached to the adapter 506 a transparent viewing portarea 514 is formed. Within the viewing port area 514, a visual flowindicator 516 is positioned. The visual flow indicator 516 has a pair oflower slots 518 that receive a pair of ridges 520, 522 formed within themouthpiece 508. Once the ridges 520, 522 are received in the slots 518,the visual flow indicator 516 is permanently attached to the ridges 520,522 by using an adhesive.

In operation, the patient activates the storage unit 502 by inhalingthrough the mouthpiece 508. Upon inhalation, the liquid within thehousing 502 is introduced by the opening (not shown) of the exit port504 to a downstream path along which the substance travels through theinterface and the mouthpiece 508 to reach the patient. Thus, theinterface 506 and mouthpiece 508 each operate as conduits for theinhaled substance. During inhalation the upper part of the visual flowindicator 516 will pivot downward to a horizontal position. If thepatient is not inhaling or fails to inhale above a specified rate ofinhalation, the upper part of the visual flow indicator 516 will remainsin a vertical position blocking an opening of the housing 510. The rangeof motion of the visual flow indicator 516 is preferably the same asthat of the visual flow indicators 138,138′, 338 and 412 mentionedpreviously.

As described previously, a visual flow indicator according to thepresent invention can be used in a variety of aerosol delivery systems.In each of the described systems, there is a common way to explain thepresent invention to encompass each of the previously described aerosoldelivery systems. In particular, the aerosol delivery systems can eachbe thought of as containing a flow indicating system where the portionof the delivery system, such as an interface or a chamber housing, thatis attached to the view port area is deemed a conduit. The conduitdefines an interior space along which a substance, such as anaerosolized medication, primarily flows along a flow path defined withinthe interior space. The flow indicating mechanism includes a flowindicator, such as the flow indicators described in FIGS. 1-42, that ispositioned within the conduit so as to be viewed via the viewing port,but is positioned substantially outside of the flow path so as to not tosubstantially interfere with the flow of the substance along theinterior space.

The embodiments of the invention disclosed herein are presentlyconsidered to be preferred, various changes and modifications can bemade without departing from the spirit and scope of the invention. Asnoted, the discussion above is descriptive, illustrative and exemplaryand is not to be taken as limiting the scope defined by any appendedclaims, and all changes that come within the meaning and range ofequivalents are intended to be embraced therein.

1-50. (canceled)
 51. A delivery system comprising: a conduit comprisinga chamber having an interior volume of space formed within said chamberand an opening communicating with said interior volume at a downstreamend of said chamber, wherein said opening defines at least in part aflow path and wherein said opening has a cross sectional area; a viewingport connected to said conduit, wherein said viewing port allowsvisualization of an internal space defined at least in part by saidviewing port; and a flow indicator positioned within said internal spaceof said viewing port and visible through said viewing port, wherein saidflow indicator is positioned substantially outside of said flow path,said flow indicator comprising a moveable portion with a surface influid communication with said flow path, wherein said moveable portionis moveable in response to an inhalation pressure applied thereto, andwherein said surface of said moveable portion has a surface area lessthan said cross sectional area of said opening.
 52. The delivery systemof claim 51 further comprising a one-way valve positioned downstream ofsaid opening.
 53. The delivery system of claim 52 wherein said flowindicator is attached to said valve.
 54. The delivery system of claim 51further comprising a baffle member positioned adjacent said opening withat least a portion of said baffle member being positioned in said flowpath.
 55. The delivery system of claim 51 wherein said moveable portionof said flow indicator has a length of between 5 mm and 20 mm.
 56. Thedelivery system of claim 55 wherein said length is between 7 mm and 11mm.
 57. The delivery system of claim 55 wherein said moveable portion ofsaid flow indicator has a width of between 5 mm and 20 mm.
 58. Thedelivery system of claim 57 wherein said width is between 8 mm and 12mm.
 59. The delivery system of claim 51 wherein said moveable portion ofsaid flow indicator has a first end portion connected to said conduitand a second end portion opposite said first end, said second endportion comprising a free edge.
 60. The delivery system of claim 59wherein said free edge is rounded.
 61. The delivery system of claim 51wherein said moveable portion of said flow indicator has a thickness of0.1 mm to 2 mm.
 62. The delivery system of claim 61 wherein saidthickness is 0.15 mm to 1 mm.
 63. A method of determining whether apatient is inhaling when using a delivery system comprising: inhalingthrough a patient interface; moving a substance along a flow paththrough an opening of a chamber from an interior space of said chamberin response to said inhaling, wherein said opening has a cross sectionalarea; and moving at least a portion of a flow indicator positionedsubstantially outside of said flow path in response to said inhaling,wherein said at least said portion of said flow indicator being movedhas a surface in fluid communication with said flow path, wherein saidsurface has a surface area less than said cross sectional area of saidopening.
 64. The method of claim 63 further comprising moving saidsubstance along said flow path through a one-way valve positioneddownstream of said opening in response to said inhaling.
 65. The methodof claim 63 wherein said at least said portion of said flow indicatorbeing moved has a length of between 5 mm and 20 mm.
 66. The method ofclaim 65 wherein said length is between 7 mm and 11 mm.
 67. The methodof claim 65 wherein said at least said portion of said flow indicatorbeing moved has a width of between 5 mm and 20 mm.
 68. The method ofclaim 67 wherein said width is between 8 mm and 12 mm.
 69. The method ofclaim 63 wherein said at least said portion of said flow indicator beingmoved has a thickness of 0.1 mm to 2 mm.
 70. The method of claim 69wherein said thickness is 0.15 mm to 1 mm.